1. Field of the Invention
This invention relates to the removal of iron and manganese from groundwater. More particularly, this invention relates to the removal of iron and manganese released from the treatment media of a primary in-situ groundwater treatment system.
2. Description of Related Art
Groundwater in many localities has become contaminated by both natural and manmade impurities. Due to the considerable reliance on groundwater as a primary source of potable water, treatment of polluted groundwater to remove such contaminants has gained significant interest within the last decade. Many treatment systems for the removal of groundwater contaminants have been proposed, including pump-and-treat systems, well injection of treatment agents, and in-situ treatment. Due to the significant cost savings, in-situ treatment of groundwater has drawn considerable interest in recent years. In-situ treatment of groundwater is discussed in NEW APPROACH TO IN-SITU TREATMENT OF CONTAMINATED GROUNDWATERS; McMurty et at., Environmental Progress 1985.
McMurtry discusses the use of permeable barrier walls placed in trenches excavated into native aquifers to treat contaminated groundwater. The permeable barrier contains appropriate treatment media, such that the quality of the contaminated groundwater flowing through the media is significantly improved. McMurtry states that most in-situ groundwater treatments will be in isothermal, anaerobic, reducing environments. Many in-situ groundwater treatment systems take advantage of this anaerobic, reducing environment, in conjunction with the selected treatment material to remove or transform the chemical contaminants in the groundwater into nonhazardous material. Typically treatment materials are limestone, activated carbon, active metals, or biological agents. These in-situ treatment systems, while removing or neutralizing many dangerous contaminants, may add other manmade contaminants to the groundwater. For example, a common treatment material for in-situ treatment is elemental or zero valent iron. While removing many contaminants, elemental iron adds iron and other metallic impurities (e.g., manganese) to the groundwater. Removal or neutralization of these manmade impurities from groundwater is essential in returning groundwater in a native aquifer to a useable state.